Embodiments of the invention relate to resonant circuits; particularly but not exclusively the embodiments relate to resonant circuits in RPID (radio frequency identification) responsive to a wide frequency range. A controllable electric resonator comprising an inductor coupled to a first capacitor to form a resonant circuit, the resonator further comprising a controllable element, a second capacitor controllable coupled across said first capacitor by said controllable element, and a control device to control said controllable element such that a total effective capacitance of said first and second capacitor varies over a duty cycle of an oscillatory signal on said resonator.
Legal claims defining the scope of protection. Each claim is shown in both the original legal language and a plain English translation.
1. A controllable electric resonator comprising an inductor coupled to a first capacitor to form a resonant circuit, the resonator further comprising a controllable element and a second capacitor, said controllable element arranged to control a total effective capacitance of said first and second capacitors, said resonant circuit comprising said total effective capacitance, the resonator further comprising a control device to provide a voltage to control said controllable element, said voltage substantially constant over a cycle of oscillation of a signal on said resonator, wherein the controllable element comprises a transistor having a gate terminal configured to receive said voltage, a source terminal configured to receive a first resonance waveform of said resonant circuit and a drain terminal configured to receive a second resonance waveform of said resonant circuit, the transistor is configured to switch when a difference between said voltage and said received first resonance waveform on said source terminal reaches a threshold voltage of the transistor, the transistor thereby configured to turn on and off during said cycle of oscillation to vary said total effective capacitance of said first and second capacitors over said cycle of oscillation.
A controllable electric resonator includes an inductor and a first capacitor forming a resonant circuit. A transistor acts as a controllable element, switching a second capacitor across the first capacitor. A control voltage, substantially constant during one oscillation cycle, is applied to the transistor's gate. The transistor's source and drain receive different waveforms from the resonant circuit. The transistor switches on and off when the voltage difference between its gate and source reaches a threshold, thereby varying the total capacitance (first and second capacitors) during the oscillation cycle, thus affecting the resonant frequency.
2. A controllable electronic resonator as claimed in claim 1 wherein said control device comprises a bias circuit for said transistor.
The controllable electronic resonator described above, with its transistor-switched capacitor, uses a bias circuit to set the operating point of that transistor. This bias circuit ensures the transistor functions correctly in controlling the effective capacitance. This circuit supports the functionality of Claim 1.
3. A controllable electronic resonator as claimed in claim 2 wherein said transistor comprises a MOS transistor.
The controllable electronic resonator, with its transistor-switched capacitor and bias circuit (as described in claims 1 and 2), uses a MOS transistor as the switching element. This specific type of transistor is used to control the effective capacitance.
4. A controllable electronic resonator as claimed in claim 2 further comprising a power supply circuit to derive a power supply for said bias circuit from said oscillatory signal.
The controllable electronic resonator, including its transistor-switched capacitor and bias circuit (as defined in claims 1 and 2), includes a power supply that derives power for the bias circuit from the oscillatory signal present in the resonant circuit. This eliminates the need for a separate power source for the bias circuit.
5. A controllable electronic resonator as claimed in claim 2 wherein said bias circuit is configured to automatically adjust a bias on said transistor to increase an amplitude of said oscillatory signal.
In the controllable electronic resonator, with its transistor-switched capacitor and bias circuit (claims 1 and 2), the bias circuit automatically adjusts the bias voltage on the transistor to increase the amplitude of the oscillatory signal in the resonant circuit. This feedback mechanism enhances the resonator's performance.
6. A controllable electronic resonator as claimed in claim 1 further comprising a third capacitor connected across said controllable element.
The controllable electronic resonator, featuring an inductor and a first capacitor to form a resonant circuit, a transistor acting as a controllable element, switching a second capacitor across the first capacitor, and a control voltage to the gate, further includes a third capacitor connected directly across the controllable element (transistor). This third capacitor can influence the switching behavior and resonant frequency.
7. A controllable electronic resonator as claimed in any preceding claim wherein said inductor has a Q of greater than 50.
In any of the above controllable electronic resonator configurations (claims 1-6), the inductor used in the resonant circuit has a quality factor (Q) greater than 50. This high Q value indicates a low-loss inductor, improving the resonator's performance.
8. A controllable electronic resonator as claimed in claim 1 further comprising a drive system to drive said oscillatory signal on said resonator.
The controllable electronic resonator, with an inductor and a first capacitor to form a resonant circuit, and a transistor acting as a controllable element, further includes a drive system. This system provides the oscillatory signal that drives the resonator, initiating and sustaining the resonance.
9. A controllable electronic resonator as claimed in claim 8 wherein said drive system includes means for converting a current drawn by said resonator into a pulse having a duration depending on said current.
The controllable electronic resonator incorporating a drive system to drive the oscillatory signal (as described in Claim 8) includes a method for converting the current drawn by the resonator into a pulse. The pulse duration is proportional to the current, providing a way to monitor resonator activity.
10. A controllable electronic resonator according to claim 1 , the controllable electronic resonator incorporated in an RFID tag, is configured to automatically select one of a plurality of frequencies of operation of said tag in response to an interrogating rf field.
The controllable electronic resonator with an inductor and a first capacitor to form a resonant circuit, and a transistor acting as a controllable element, is incorporated into an RFID tag. This RFID tag automatically selects one of several operating frequencies in response to an RF field used for interrogation.
11. A controllable electronic resonator as claimed in claim 1 incorporated into an RFID tag or tag reader.
The controllable electronic resonator including an inductor and a first capacitor to form a resonant circuit, and a transistor acting as a controllable element, is integrated into either an RFID tag or an RFID tag reader.
12. A controllable electronic resonator according to claim 1 wherein the transistor is configured to turn on and off according to a variable duty cycle; and wherein a response frequency of the resonant circuit is dependent on the duty cycle, and the response frequency of the resonant circuit automatically adjusts to a stimulus frequency.
The controllable electronic resonator, featuring an inductor and a first capacitor to form a resonant circuit, and a transistor acting as a controllable element, where the transistor switches on and off with a variable duty cycle, and the resonant circuit's response frequency depends on this duty cycle. This resonator automatically adjusts its response frequency to match a stimulus frequency.
13. A circuit as claimed in claim 12 wherein said variable duty cycle is controlled by a FET.
The circuit with a variable duty cycle controlled by a transistor (as described in Claim 12), wherein the variable duty cycle is specifically controlled by a FET (Field Effect Transistor).
14. A circuit as claimed in claim 13 wherein the FET gate voltage is kept constant and the FET source voltage varies with the amplitude of the resonance, turning the FET on and off.
The circuit where a FET controls the duty cycle (as in claim 13), the FET gate voltage is kept constant, while the FET's source voltage varies with the resonance amplitude. This causes the FET to turn on and off depending on the resonance strength.
15. A circuit as claimed in claim 13 wherein the FET gate voltage is controlled with an external voltage source.
In the circuit with a FET controlling the duty cycle (as described in Claim 13), the FET's gate voltage is controlled using an external voltage source. This allows for direct control over the switching behavior of the FET.
16. A circuit as claimed in claim 12 in a reader wherein the stimulus frequency is a sub-harmonic of a desired energizing field frequency.
The circuit, where a transistor duty cycle controls the resonance frequency (as described in Claim 12), is used in a reader. The stimulus frequency is a sub-harmonic of the desired energizing field frequency.
17. A circuit as claimed in claim 12 in a reader wherein a crystal oscillator sets the operating frequency of the energizing field.
The circuit, where a transistor duty cycle controls the resonance frequency (as described in Claim 12), is used in a reader. A crystal oscillator determines the operating frequency of the energizing field.
18. A circuit as claimed in claim 12 in a transponder.
The circuit where a transistor duty cycle controls the resonance frequency (as described in Claim 12) is used in a transponder.
19. A controllable electric resonator comprising a resonant circuit and a system for controlling the amplitude of oscillations on the resonant circuit, when the resonant circuit is driven by an oscillatory signal, the apparatus comprising: means for applying a reactive element to said resonant circuit with a variable coupling; and means for varying said coupling over a cycle of said oscillatory signal to control said amplitude of oscillations, wherein the means for varying said coupling comprises a transistor having a gate terminal configured to receive a substantially constant voltage, a source terminal configured to receive a first resonance waveform of said resonant circuit and a drain terminal configured to receive a second resonance waveform of said resonant circuit, and the means for varying said coupling is for switching the transistor when a difference between said substantially constant voltage and said received first resonance waveform on said source terminal reaches a threshold voltage of the transistor, to thereby turn the transistor on and off during said cycle to vary said variable coupling over said cycle.
A controllable electric resonator comprising a resonant circuit and a system for controlling the amplitude of oscillations. The resonator is driven by an oscillatory signal. It utilizes a reactive element applied with a variable coupling. This coupling is varied during each cycle of the oscillatory signal to control the oscillation amplitude. A transistor serves as the means for varying coupling, its gate receiving a constant voltage. The source and drain receive resonant circuit waveforms. The transistor switches when the gate-source voltage difference reaches its threshold, thus altering the coupling.
20. A method of controlling a resonant frequency of a resonant circuit of a controllable electric resonator to substantially match said resonant frequency to a frequency of an external waveform, the controllable electric resonator comprising an inductance coupled to a capacitance, the capacitance having a first component of capacitance and a second component of capacitance coupled to a field effect transistor (FET) switch, the method comprising: turning on and off said FET switch during a period of oscillation of a signal on said resonant circuit to vary a total effective capacitance of said first and second components of capacitance, said turning on and off having a duty cycle that is a fraction of a period of oscillation of said resonant circuit; and controlling said duty cycle in response to a signal level of a waveform of an oscillation of said resonant circuit; wherein the FET switch comprises a source arranged to receive a first resonance waveform of said resonant circuit, a drain arranged to receive a second resonance waveform of said resonant circuit and a gate arranged to receive a voltage that is substantially constant over said period of oscillation of said resonant circuit, and wherein said duty cycle controlling comprises providing a voltage between said gate and said source of said FET dependent upon an instantaneous level of said waveform of said oscillation of said resonant circuit such that the FET switches state when said voltage between said gate and said source reaches a threshold voltage of the FET.
A method for controlling the resonant frequency of a resonator to match an external waveform. The resonator contains an inductor and a capacitor split into two components, with a FET switch controlling one capacitor component. The FET switch turns on and off during a signal oscillation period, altering the total capacitance with a certain duty cycle (fraction of the period). The duty cycle is dynamically adjusted based on the resonant circuit's oscillation waveform. The FET's gate voltage is constant. Duty cycle is controlled by changing the gate-source voltage of the FET based on oscillation levels, so the FET switches state when this reaches the threshold.
21. A method as claimed in claim 20 wherein a relative phase of said waveform of said oscillation of said resonant circuit and of said external waveform changes responsive to a signal level of said external waveform.
The method for controlling the resonant frequency of a resonator via FET duty cycle control (as described in Claim 20), also allows for the relative phase between the resonator's waveform and the external waveform to change according to the external waveform's signal level.
22. A method as claimed in claim 20 wherein said external waveform comprises a waveform of an rf electromagnetic field.
In the resonant frequency control method using a FET duty cycle (as described in Claim 20), the external waveform is derived from an RF electromagnetic field.
23. A method as claimed in claim 22 further comprising and extracting energy from said resonant circuit.
The resonant frequency control method using a FET duty cycle responding to an RF field (as described in claim 22), also includes extracting energy from the resonant circuit.
24. A method as claimed in claim 23 wherein a relative phase of said waveform of said oscillation of said resonant circuit and of said external waveform changes responsive to as signal level of said external waveform, and wherein said relative phase adjusts to limit said extracted energy as said energy in said rf electromagnetic field increases.
In the resonant frequency control method using a FET duty cycle responding to an RF field and extracting energy (as in Claim 23), the relative phase between the resonator and external waveforms changes depending on the RF field's signal level. This relative phase adjusts to limit energy extraction as the RF field's energy increases, preventing overload.
25. A method as claimed in claim 20 wherein said external waveform comprises a waveform derived from a crystal oscillator.
In the resonant frequency control method using a FET duty cycle (as described in Claim 20), the external waveform is derived from a crystal oscillator.
26. A method as claimed in claim 25 , further comprising outputting an rf signal derived from said oscillation of said resonant circuit to provide an rf signal source.
The method of controlling a resonant circuit with a FET duty cycle, using a crystal oscillator signal as reference (as described in Claim 25), includes outputting an RF signal from the resonator's oscillation, providing an RF signal source.
27. An apparatus comprising: a resonant circuit and a system for automatically adjusting a resonant frequency of the resonant circuit when the resonant circuit is driven by an oscillatory signal; means for applying a reactive element to said resonant circuit with a variable coupling; and means for varying said coupling within a cycle of said oscillatory signal so as to change the resonant frequency of the resonant circuit.
This invention relates to resonant circuit systems, specifically addressing the challenge of maintaining or adjusting resonant frequency in response to varying operating conditions. The apparatus includes a resonant circuit and an automatic adjustment system that modifies the resonant frequency when the circuit is driven by an oscillatory signal. The adjustment is achieved through a reactive element, such as a capacitor or inductor, coupled to the resonant circuit with variable coupling strength. The coupling is dynamically adjusted within each cycle of the oscillatory signal, allowing the resonant frequency to be fine-tuned in real time. This variable coupling mechanism enables precise control over the resonant frequency, compensating for environmental or operational changes that might otherwise detune the circuit. The system ensures stable performance by actively modifying the reactive element's influence on the circuit, thereby maintaining optimal resonance. This approach is particularly useful in applications where resonant circuits must operate under fluctuating conditions, such as in wireless power transfer, radio frequency (RF) communication systems, or sensor networks. The invention provides a method to dynamically adapt the resonant frequency without requiring external intervention, improving efficiency and reliability in resonant circuit applications.
28. A controllable electronic resonator including a circuit for controlling a resonant frequency of the resonator to substantially match said resonant frequency to a frequency of an external waveform, the resonator comprising an inductance coupled to a capacitance, the capacitance having a switched component of capacitance, the circuit comprising means for controlling a duty cycle of said switched component of capacitance in response to a signal level of a waveform of an oscillation of said resonator.
A controllable electronic resonator has a circuit to control its resonant frequency to closely match an external waveform. The resonator includes an inductor and a capacitor with a switched component. The circuit controls the duty cycle of the switched capacitance based on a signal level of the resonator's oscillation waveform.
29. A controllable electronic resonator as claimed in claim 28 , configured to extract energy from an rf electromagnetic field.
The controllable electronic resonator, featuring a circuit for controlling its resonant frequency with a switched capacitor component whose duty cycle is responsive to a signal level of a waveform (as described in Claim 28), is designed to extract energy from an RF electromagnetic field.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
December 7, 2006
June 25, 2013
Browse 5M+ US patents with plain-English claim translations and AI-generated analysis.